Video Transcription:

What Causes A Dirty Furnace Air Blower & Evaporator Coil?

Hi, I’m Scott from A/C Doc Heating & Cooling. And I’m here to talk to you a little bit about what happens to a system when the air filters weren’t changed and you have problems with a bad air quality in the home and it gets into the system.

Always…

Again, always when you’re working on the system, turn the power off. OK? This has been disconnected for the purpose and use of my video.

The Air Blower

This is the blower section and this is where the air flow goes through the furnace and you would only have your return air duct here. It goes into the furnace.

But when we pull it out and don’t see there’s a filter in there or an impacted filter then we look at this blower. We already disconnected all the wires so it’s easy for me to pull this out. I’m going to show what I’m working on so you can see what I’m talking about.

But when we pull these blowers out or we get our inspection men and look in there and you see, this one, I pulled it out so many times. This whole back of this motor was impacted with this, I don’t know if it’s dog hair or cat hair, whatever, this junk that got all up in here. But this whole back was impacted. So it does several things.

The holes are for air to get in to cool the motor so the motor overheats. It wears the bearings out prematurely. It caused it to draw more power using more electricity and it will prematurely fail this motor.

The other thing that would happen with all the dust and the dirt, if you can see on these wheels, all these wheels, these veins on this have a contour and the dirt does not get distributed evenly. It builds up in all different locations. And what it does is it throws that wheel out of balance and then it shakes and vibrates the furnace. It also ruins the bearings again in the fan motor, a premature failure because this is all like I said out of balance and it starts shaking and vibrating. And the way to correct this is and it can be fixed but it’s an expensive repair especially if lose the motor because of it.

So, all of these need to be pulled out. All these wires need to be disconnected. We would take this motor out. If the motor was still good, we would blow this out with compressed air or nitrogen. We would take all the electronics off of it obviously because we can’t spray water on that. Take this wheel out. We would acid clean this whole assembly and then put it back in and it would look basically like brand new. It is a fairly expensive and time-consuming procedure provided you didn’t lose the motor. OK?

The Evaporator Coil

Now, the next thing that I’m going to look at when I have this out, and I’m a small guy and the width of this furnace, I could actually climb in there and what I’m looking at, when I see that that blower that dirty, normally, it’s a good indication that the evaporator coil and that’s on top of the furnace is also impacted.

The air goes into the blower section and then up through across the heat exchanger and that’s what brings the heat into your house in the wintertime when the furnace is running. Then it goes through the evaporator coil which is what gives you the cooling and the humidifying effect in the summer time. But that coil up here has very tight little fins.

So I would lie in here and look up through with my flashlight. I would inspect the heat exchanger for holes and cracks. And I have to also look at that coil to see if it’s dirty or impacted. And then like I said, normally with my experience, when you look at a blower like that, the coil is going to be impacted.

We’re going to move this. I can bring a coil over and show you. And this system also – and keep in mind, this is not what you should be doing in your house because of this is all connected to the ductwork, refrigerator lines, the drain lines. So you can’t just pick this up and put it on your work bench that easy obviously. It’s a big deal.

As you can see, this coil is probably about 50% impacted with dog or cat hair, lint, whatever. Do you see how bad this is? And the name of the game especially with the air conditioning is heat transfer. I’m really not going to get into it but heat transfers into this coil when 50% of it is impacted.

And the same thing, the furnace air has to be delivered through that too. So it restricts the air flow, caused the furnace to overheat. It doesn’t give you the volume of air out. So it’s just a waste of energy significantly whether you’re running heat or the cooling. So it wouldn’t matter which mode you’re running in because all the air got to get through this coil. So when this coil gets dirty, it affects both, the furnace operation and the air conditioning operation.

How We Repair A Dirty Furnace Like This

Now, the correct way to do it, but you could go into the front of this furnace and try to brush this off. But really, you’re just going to get the surface dirt off of this. If you can see, this coil is pretty easy to bend. And if a guy goes in here with a wire or brush or something, goes the wrong way, he’s going to destroy all those fins. And then the water doesn’t trickle down through the drainage and things of that nature. It caused a lot of problems.

The right way to do it and what I would recommend is we would cut the refrigerator lines. Take the refrigerant now or pump down the system. Pull this coil out. Take it in the backyard, acid clean it and then rinse it out with those and put it back in. And that’s because those coils are about an inch and a half and two inches wide. So like I said, you’re just going to get the surface stuff out even if you go on with a pretty good brush. I wouldn’t recommend it.

To do it right, you take the refrigerant out of the system or pump the system down but you still got to recover a little bit of refrigerant. It’s just a time-consuming process and I wouldn’t recommend it. At this point, it’s just – we’re replacing the coil over in this application. We replace the system because the blower is dirty, this is dirty and there are several other problems. But it’s a 10-year-old system that got ripped out and a lot of this could have been prevented.

AC Doc Heating & Cooling

So hopefully, that’s helpful. Again, I’m Scott from AC Doc.

If you need help with your furnace, please call us on 703 406 9446. We are based in Sterling and service clients all around Northern Virginia.